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The Population of a City Increases Each Year by 4% of What It Had Been at the Beginning of Each Year. If the Population in 1999 Had Been 6760000, Find the Population of the City in (I) 2001 (Ii) 1997.

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Question

The population of a city increases each year by 4% of what it had been at the beginning of each year. If the population in 1999 had been 6760000, find the population of the city in (i) 2001 (ii) 1997.

Sum
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Solution

\[(i)\]
Population of the city in 2001 = P \[\left( 1 + \frac{R}{100} \right)^2 \]
\[ = 6760000 \left( 1 + \frac{4}{100} \right)^2 \]
\[ = 6760000 \left( 1 . 04 \right)^2 \]
\[ = 7311616\]
Thus, Population of the city in 2001 is 7311616.
\[(ii)\]
Population of the city in 1997 = P \[\left( 1 + \frac{R}{100} \right)^{- 2} \]
\[ = 6760000 \left( 1 + \frac{4}{100} \right)^{- 2} \]
\[ = 6760000 \left( 1 . 04 \right)^{- 2} \]
\[ = 6250000\]
Thus, Population of the city in 1997 is 6250000.

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Chapter 14: Compound Interest - Exercise 14.4 [Page 28]

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R.D. Sharma Mathematics [English] Class 8
Chapter 14 Compound Interest
Exercise 14.4 | Q 15 | Page 28

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